Conventionally, an electric power steering device, in which the drive unit assists a steering operation of a driver, has the motor and its control unit housed in one body. Such steering device is described in Japanese Patent Laid-Open No. 2003-204654 (JP '654). The steering device of JP '654 has an electrical connection between the motor and the control unit enabled by fastening a bus bar extending from the control unit on a winding wire terminal in a motor case by using a screw. In such structure, the bus bar on the control unit side and the winding wire terminal on the motor side can be easily separated from each other to allow, for example, the replacement of one of the two parts when the parts are broken.
However, since the bus bar from the control unit and the winding wire of the motor are coupled inside of the motor case, the structure of the steering device of JP '654 may require the motor to have a larger size. Further, when the screw for fastening the bus bar on the winding wire terminal is removed, the drive unit has to be removed from a column shaft that is connected to a steering wheel. In other words, such structure does not allow an easy removal of the control unit without first removing the drive unit from the column shaft.